(continued)
Unique New Magnesium/Aluminum
Engine Construction
With the N52 engine, BMW introduces a unique and pioneering engine structure:
magnesium/aluminum composite construction, the first in a contemporary
automobile. Structurally, the all-new engine block consists of three major
castings:
- Bedplate (magnesium alloy). This casting forms the lower portion of
the block (crankcase), and is similar in concept to a construction element
found in some racing engines – as well as the 500-hp V-10 engine powering the
new BMW M5.
- Upper crankcase (magnesium alloy). Joining the bedplate at the
level of the crankshaft (main) bearings, this too is a weight-saving casting.
Mounted onto the bedplate from above; combines with the bedplate to form the
cylinder block’s outer shell. The result is an ultra-rigid, yet remarkably
light engine structure.
- Insert (aluminum alloy). Forms the cylinders and their coolant
passages. Analogous to the entire blocks of BMW‘s V-8, V-10 and V-12 engines,
silicon particles are cast into this insert; a “soft honing” machine removes
just enough of the aluminum to leave the crystals as ultra-hard cylinder
surfaces.
The engine’s camshaft cover is of weight-saving magnesium. The VANOS
sprockets, via which the camshaft chain drives the two variable-valve-timing
mechanisms, are newly of aluminum. And the chain camshaft drive – a
high-durability, low-maintenance feature of all current BMW engines – has an
aluminum chain tensioner that also saves weight. Instead of being a separate
casting, the camshaft drive’s housing is integrally cast into the magnesium
structure, eliminating a production step and sealing components. As one final
weight-reducing element, the exhaust headers’ flanges are formed from 2-mm-thick
steel, significantly lighter than the 12-mm flanges used previously; for a
secure seal of this steel to the aluminum head, graphite rings are employed.
5 Series Interior
At the beginning of model year ’05, several detail refinements were made to the
5 Series interior:
- The steering-wheel’s leather rim was improved.
- The power windows’ control panel got new Soft Finish.
- Surfaces of interior trim panels were refined.
- In the 545i, the climate control’s rotary knobs were newly in Ruthenium.
Further changes to the Sedan interiors for ’06, which also apply to the new
Sports Wagon, are also subtle:
- Adoption of Ruthenium trim for the climate control’s rotary knobs (which
regulate temperature and blower speed) and the tabs with which occupants
adjust the direction of air from the center-dash outlets. Although the core of
this material is plastic, a true metallic surface is applied galvanically in
several layers, with a clearcoat on top to protect against corrosion. As one
expects with a metallic surface, Ruthenium is cool to the touch. After being
applied to the power-window panel for ‘05, Soft Finish now enhances the
steering wheel’s spokes – the areas outboard of the wheel’s padded center.
- Leather handbrake grip, replacing leatherette.
Character of the 5 Series
The 5 Series has long been one of BMW’s true core products, elegantly defining
the middle of the line with compact exterior dimensions, ample interior space
and a masterfully calibrated blend of sport and luxury. Appearing in ’04 in its
current generation, the Series maintained trim exterior size while increasing
interior space and introducing new technologies – including an aluminum
front-end structure, available Active Steering and Active Roll Stabilization,
evolved aluminum suspension and an evolved iDrive control system.
That the current generation carries on the 5 Series tradition brilliantly is
supported by this quote from Motor Trend’s March 2005 issue: “Here’s a
thoroughbred, the product of decades of setting the benchmark all other
automakers’ sport sedans aspire to. Just look at the stance, the way the body
sits on the chassis, ready to pounce on any opportunity to show its stuff on a
challenging stretch of road. The smoothness and flexibility of BMW inline-sixes
are legendary, and the 225 horses of the 2979-cc engine seem more spirited than
their numbers might otherwise suggest. And BMW is one of the only automakers
courageous enough to offer a 6-speed manual gearbox in a $50,000 sedan.”
With its new 6-cylinder engines, available xDrive and the new Sports Wagon to
extend its capabilities, the 5 Series now moves on to even greater glory as
today’s representative of this fine tradition.
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